This study analyzes the occurrence of bile salt hydrolase in fourteen strains belonging to the genus Bifidobacterium. Deconjugation activity was detected using a plate test, two-step enzymatic reaction and activity staining on a native polyacrylamide gel. Subsequently, bile salt hydrolases from B. pseudocatenulatum and B. longum subsp. suis were purified using a two-step chromatographic procedure. Biochemical characterization of the bile salt hydrolases showed that the purified enzymes hydrolyzed all of the six major human bile salts under the pH and temperature conditions commonly found in the human gastrointestinal tract. Next, the dynamic rheometry was applied to monitor the gelation process of deoxycholic acid under different conditions. The results showed that bile acids displayed aqueous media gelating properties. Finally, gel-forming abilities of bifidobacteria exhibiting bile salt hydrolase activity were analyzed. Our investigations have demonstrated that the release of deconjugated bile acids led to the gelation phenomenon of the enzymatic reaction solution containing purified BSH. The presented results suggest that bile salt hydrolase activity commonly found among intestinal microbiota increases hydrogel-forming abilities of certain bile salts. To our knowledge, this is the first report showing that bile salt hydrolase activity among Bifidobacterium is directly connected with the gelation process of bile salts. In our opinion, if such a phenomenon occurs in physiological conditions of human gut, it may improve bacterial ability to colonize the gastrointestinal tract and their survival in this specific ecological niche.

SummarySuccinic acid is an important C4‐building chemical platform for many applications. A novel succinic acid‐producing bacterial strain was isolated from goat rumen. Phylogenetic analysis based on the 16S rRNA sequence and physiological analysis indicated that the strain belongs to the genus Enterobacter. This is the first report of a wild bacterial strain from the genus Enterobacter that is capable of efficient succinic acid production. Co‐fermentation of glycerol and lactose significantly improved glycerol utilization under anaerobic conditions, debottlenecking the utilization pathway of this valuable biodiesel waste product. Succinic acid production reached 35 g l−1 when Enterobacter sp. LU1 was cultured in medium containing 50 g l−1 of glycerol and 25 g l−1 of lactose as carbon sources.

Ferulic acid, a very attractive natural antioxidant is present in beer in free form, but the main form is the bound form as feruloylated oligosaccharides. Previous research showed that feruloylated oligosaccharides more effectively inhibited lipid and Low Density Lipoprotein oxidation than free ferulic acid. The aim of the present study was to evaluate free and bound ferulic acid concentrations throughout the brewing process in experimental mashes (worts, beers during fermentation, maturation and storage), and to conduct a comparison in commercial beers. Another aim of the study was to investigate methods to increase levels of bound ferulic acid in beer due to the potential health benefits. Specifically, the influence of commercial enzyme preparations on both forms of ferulic acid contents was studied. Five commercial enzyme preparations during mashing were examined: Celluclast, Shearzyme, Viscozyme, Cereflo and Ultraflo. In all experimental beers, the concentrations of esterified ferulic acid were 4-6 fold higher than the corresponding free ferulic acid contents, depending on the enzyme preparation used. Ferulic acid contents in the ester form in experimental beers were in the range of 748.4 mg/hL to 1244.3 mg/hL, whereas the contents of free ferulic acid were in the range of 134.6 mg/hL to 275.2 mg/hL. Comparison of free and bound ferulic acid contents in experimental beers, produced using enzyme preparations and commercial beers found in a local market, showed that concentrations of bound ferulic acid in experimental beers were significantly higher than in commercial beers, whereas concentrations of free ferulic acid in experimental and commercial beers were comparable.

In this work, an extracellular ferulic acid esterase was produced in bioreactor cultivations of Lactobacillus acidophilus K1 strain. The enzyme was partially purified using ultrafiltration (10 kDa), dialysis (4-6 kDa) and Fast Protein Liquid Chromatography (Sepharose CM, Sephacryl S-300). A considerable increment of enzyme activity (31-fold) in the final preparation was achieved. Two distinct bands (approx. 21.5 kDa and 39 kDa) were obtained after SDS-PAGE. A high similarity of the purified enzyme (LC-MS/MS analysis) to tannase and ferulic acid esterase from Burkholderia ambifaria MEX-5 was obtained. The optimal pH and temperature for the enzyme activity were 6.3 and 37°C, respectively. The enzyme preparation effectively released phenolic acids (mainly ferulic and p-coumaric acid) from brewer's spent grain. This novel enzyme preparation can be used for the utilisation of a valuable and inexpensive by-product of the brewing industry.

Background: Members of the genus Bifidobacterium are anaerobic Gram-positive Actinobacteria, which are natural inhabitants of human and animal gastrointestinal tract. Certain bifidobacteria are frequently used as food additives and probiotic pharmaceuticals, because of their various health-promoting properties. Due to the enormous demand on probiotic bacteria, manufacture of high-quality products containing living microorganisms requires rapid and accurate identification of specific bacteria. Additionally, isolation of new industrial bacteria from various environments may lead to multiple isolations of the same strain, therefore, it is important to apply rapid, low-cost and effective procedures differentiating bifidobacteria at the intra-species level. The identification of new isolates using microbiological and biochemical methods is difficult, but the accurate characterization of isolated strains may be achieved using a polyphasic approach that includes classical phenotypic methods and molecular procedures. However, some of these procedures are time-consuming and cumbersome, particularly when a large group of new isolates is typed, while some other approaches may have too low discriminatory power to distinguish closely related isolates obtained from similar sources.